It is well known to operate inlet and exhaust valves of an internal combustion engine by means of a rotating camshaft. If the camshaft is rotated together with the crankshaft of the engine, it is not possible to alter the valve movement profile and/or timing in relation to the engine speed or loading. However, greater efficiency can be achieved by varying the valve operation with regard to the demands on the engine.
In order to give greater control over the valve actuation, it has been proposed to operate the valves using electromagnetic solenoid actuators governed by a computer-controlled engine management system. An alternative approach is described in WO 2004/097184. This relates to an electromagnetic actuator having a driven rotor which is coupled to the valve by a suitable linkage.